Normal, lactating rat mammary gland and dimethylbenz[a]anthracene (DMBA)- induced rat mammary tumor galactosyltransferase (GTase) synthesized in vitro by translating extracted messenger RNA from these respective tissues in cell-free wheat germ extract and rabbit reticulocyte lysate systems will be exploited to characterize the existence of differential internal domain- directed putative anabolic action of these enzymes in cell-cell interactions. Presently, we have found molecular weight differences and putative substrate affinity differences in nascent polypeptides synthesized in these tissues during their differential metabolic states. In these on- going studies, mammary gland and tumor cells grown in culture will be probed with substrate-liganded gel beads to determine the in situ selectivity of these putative multiforms of GTase. Enzymic-directed isotope labeled (3H-galactose and 3H-UDP-galactose) cells in culture will be harvested and subjected to subcellular fractionation for analyses by affinity chromatography, immunoprecipitation, electroblot (western transfer) and HPLC to determine the translational regulation of GTase(s) as putative markers of differences in cell-to-cell surface actions in the normal and tumorous states of mammary cells.